自定义一个NavigationController

- (void)viewDidLoad {
   [super viewDidLoad];
   UIGestureRecognizer *gesture = self.interactivePopGestureRecognizer;
    gesture.enabled = NO;
    UIView *gestureView = gesture.view;
    
    UIPanGestureRecognizer *popRecognizer = [[UIPanGestureRecognizer alloc] init];
    popRecognizer.delegate = self;
    popRecognizer.maximumNumberOfTouches = 1;
    [gestureView addGestureRecognizer:popRecognizer];
    
#elif USE_方案0
    /**
     *  获取系统手势的target数组
     */
    NSMutableArray *_targets = [gesture valueForKey:@"_targets"];
    /**
     *  获取它的唯一对象，我们知道它是一个叫UIGestureRecognizerTarget的私有类，它有一个属性叫_target
     */
    id gestureRecognizerTarget = [_targets firstObject];
    /**
     *  获取_target:_UINavigationInteractiveTransition，它有一个方法叫handleNavigationTransition:
     */
    id navigationInteractiveTransition = [gestureRecognizerTarget valueForKey:@"_target"];
    /**
     *  通过前面的打印，我们从控制台获取出来它的方法签名。
     */
    SEL handleTransition = NSSelectorFromString(@"handleNavigationTransition:");
    /**
     *  创建一个与系统一模一样的手势，我们只把它的类改为UIPanGestureRecognizer
     */
    [popRecognizer addTarget:navigationInteractiveTransition action:handleTransition];
}

实现代理

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
    /**
     *  这里有两个条件不允许手势执行，1、当前控制器为根控制器；2、如果这个push、pop动画正在执行（私有属性）
     */
    return self.viewControllers.count != 1 && ![[self valueForKey:@"_isTransitioning"] boolValue];
}